(i) Field of the Invention
The present invention relates to the improvement in or relating to the method of correcting a deformation left in the rolled-down strip product such as a cold rolled steel strip, etc. (hereinafter referred to as "the strip product") by way of the tension regulator or leveling equipment.
(ii) Description of the Prior Art
It is generally known that the rolled-down strip product suffers from such defects of distortion as a partial elongation appeared as edge-waves and center buckles of a strip, and as a partial bending appeared as an L-shaped and C-shaped warpings, etc. It is naturally inevitable that such defects of distortion would not only spoil the appearance of the sheet products, thus degrading the commercial value of the product, but also hampering the efficiency of feed throughout the procedures of roll-down operation on the strip product, and thus eventually rendering an obstackle to the automation of the entire strip production line. Also, this defect would then bring a further cause of distortion in the subsequent secondary working procedures. In this connection, there have been proposed the introduction of a tension regulator or leveler in the attempt for the correction of such defects of distortion in the production of the strip product.
Referring first to FIG. 1, there is shown the general layout of the typical tension leveling equipment of conventional construction. As shown in this drawing figure, there are seen input bridle unit 3 and output bridle unit 4 provided on the input and output sides of a leveling mill 2, respectively, through which bridle units 3 and 4 an extension of strip 1 is fed under tension in the direction shown by arrows. By aid of a plurality of working rolls 5, 6, 7, 8 and shift rolls 9, 10 which are arranged vertically in a zigzag fashion above and below the extension of the strip 1 along the longitudinal direction of the entire leveling mill 2, the strip 1 is subjected in sequence to the repeated procedures of bending throughout the whole extension of the leveling mill 2. With this sequence of procedures, the strip 1 is rendered the permanent elongation which is required for smoothing out its distortion, thus finishing the due correction of distortion involved in the strip 1, accordingly.
It is of the general practice that among the series of rolls provided in the leveling mill 2, those rolls as disposed above and along the extension of strip 1, that is, a unit of work roll 5 and paired back-up rolls 5a, a work roll 7, a pair of deflector rolls 8a and a shift roll 9 are fixed in their vertical positioning on one hand, and that those as disposed below and along the extension of strip 1, that is, a unit of work roll 6 and its paired back-up rolls 6a, a pair of deflector rolls 7a, a work roll 8 and a shift roll 10 are respectively mounted shiftably up and down by way of such elevating units 11, 12, 13, 14 as, for instance, an electrically operated jack, on the other hand. With this arrangement, these rolls 6, 6a, 7a 8 and 10 are designed to be shiftable in their locations in the vertical directions so that the relationship of intermeshing thereof may be adjusted accordingly. Furthermore, it is arranged that the shift rolls 9 and 10 are mounted shiftably in the mutually opposite directions of their axes by aid of a roll shifting drive not shown. Further to such mounting for these shift rolls 9, 10, it is known as disclosed in the Japanese patent application Laid-open No. 153622/1980 that they are formed with crownings at one ends thereof in the mutually opposite positions, respectively, and that these rolls 9, 10 may be shifted mutually in the opposite directions along their axes in accordance with the width dimension, the mechanical property in the width and the distribution of thickness of the strip 1. This arrangement is designed specifically for the provision that the distance of the crowning portions of these rolls working upon the widthwise edges may be adjusted accordingly, thereby allowing the arbitrary changes of the distribution of tensions in the widthwise direction of the strip. In this drawing, there is also shown support rolls 15 and 16.
On the other hand, it is designed for rendering a required rate of elongation on the extension of strip 1 that there is given a difference in velocities of rotation of the both input and output bridle units 3 and 4 which corresponds to a predetermined extent of elongation. More specifically, the output bridle unit 4 is driven by a single main motor 17 through a bevel gear 18a and a pinion stand 19a provided for this particular bridle unit. At the same time, the input bridle unit 3 is arranged to be driven by one and the same main motor 17 through a pinion 20, a ring gear 21a of a planetary-gear unit 21, a bevel gear 18b connected operatively to the solar-revolution shaft 22 of the planet gear unit and through a pinion stand 19b. Also, a stretching motor 23 which is a direct current motor is connected operatively to a solar gear of the planetary gear unit 21. With such arrangement, it is designed to obtain a required difference in the circumferential velocities of the both input and output bridle units 3, 4 through the control of the rotating speed of this stretching motor 23, accordingly. There are also shown slipping clutches 24 provided in each of the pinion stands 19a and 19b, respectively.
It is also shown that this stretching motor 23, each of the elevating units 11, 12, 13, 14 noted above and the roll shifting drive are connected operatively to an operation processsor 25. The operation processor 25 is operated in processing of a given condition of specifications 26 such as the width, thickness and proof stress or yield strength, and the extent of edge-wave and center buckle of the strip 1, so that the amount of vertical shift (intermeshing) between the rolls 6, 6a, 7a, 8, 10, the amount of axial shift (extent of shifting) of the shift rolls 9, 10, the revolutionary velocity of the stretching motor 23 or the required rate of elongation of the strip 1 may be determined to be set.
As reviewed fully hereinbefore, it is known arranged in the conventional tension leveling equipment that the strip 1 is fed through the leveling mill 2 for the corrective procedures of its distortion, only after presetting such data as an extent of intermeshing and axial shift of the rolls involved and a required rate of elongation of the strip 1 in correspondence with a variety of given conditions of specification 26 on the strip 1 to be entered into the operation processor 25.
Recent years, however, the requirements for the improvement in the quality of the strip product have been growing more and more strict, and then this type of distortion removing process of the strip product by way of presetting the conditions such as the rate of intermeshing and the extent of vertical shifting of the rolls and the rate of elongation of a strip (which is called as the presetting control process) cannot meet such increasing requirements accordingly. More specifically, while there is given a coil of strip of an identical dimension, it is generally inevitable that there may exist a substantial struggling in the mechanical properties of a strip owing to the possible segregation of the chemical components in the longitudinal and widthwise directions thereof, in the irregular treating temperatures of the strip while in the rolling procedures, in the thickness dispersion of the strip, etc. As a consequence, therefore, there is available no effective means in correspondence to the fluctuations in such conditions as noted above for the due correction of distortions of the strip product with the conventional presetting control process.